The conversion of olefins over ZSM-5 type catalyst is known in the art and is the subject of many patents. A wide range of techniques have been disclosed leading to the improved production of gasoline, distillates and lubricant range hydrocarbons through catalyst modifications, unique process conditions and the like. For example, U.S. Pat. No. 4,227,992 and the patents therein are excellent examples of the prior art in connection with this general subject.
In U.S. Pat. No. 4,517,399 to Chester, olefins are oligomerized over ZSM-5 type zeolite catalyst to obtain high viscosity index lubricating oils wherein the improvement involves the use of large crystal size ZSM-5.
In U.S. Pat. No. 4,547,613 to Garwood et al., light olefins are converted into a high viscosity index lubricating oil by contacting at elevated pressure with ZSM-5 type catalyst that has been conditioned by treatment with a light hydrocarbon gas at low pressure and elevated temperature.
In U.S. Pat. No. 4,520,221 to Chen, a process is disclosed providing high yields of lubricating oils with substantially higher viscosity indices from the conversion of light olefins such as propylene using ZSM-5 catalyst. The results are achieved by removing the surface acidity of the catalyst by treatment with a bulky amine. U.S. Pat. No. 4,568,786 to Chen et al. discloses a continuous process for the conversion of olefins to heavier hydrocarbons containing a lubricant fraction of high viscosity index by cofeeding a surface deactivating agent such as a bulky amine. In the U.S. Pat. No. 4,150,062 to Garwood et al., an olefins conversion process is described to produce high octane gasoline using aluminosilicate zeolite catalyst, including ZSM-5. Large molar equivalents of water, preferably about 0.5 to about 5 moles of water per mole of olefin feedstock, are cofed with olefin in the process.
It is an object of the present invention to provide an improved process for upgrading olefins to lubricant oils of high viscosity index. In particular, it is an object of the present invention to provide a process for the upgrading of olefins to lubricant oils using medium pore shape selective aluminosilicate zeolite type catalysts without the use of costly organic surface deactivating agents or complex process conditions.